Eu3+在La2O2S中的长余辉发光

The new Eu³⁺ doped lanthanum oxysulfide phosphors,which have the orange-red long afterg low emission,were synthesized by solid-state reaction method.The synthesized phosphors were characterized by X-ray diffraction.The excitation and emission spectra,afterglow spectra and afterglow decay curves were examined.XRD confirmed the phosphor as pure phase La₂O₂S.The phosphors showed typical transitions ⁵D_J(J=0,1) → ⁷J_J(J=0,1,2,3,4)of Eu³⁺.The photoluminescence spectra and afterglow spectra presented the regular alteration with various Eu³⁺ concentration, due to cross relaxation between energy levels of Eu³⁺. In addition, we studied the effects of activator concentration and dopants species on the afterglow property. The data showed afterglow result was the best with 2 % Eu³⁺ and doped with Mg²⁺ and Zr⁴⁺. A prominent phosphorescence can be seen in this phosphor after illuminated with UV light.     

锐钛矿型TiO2水溶胶的低温制备及其表征

Anatase titanium dioxide hydrosol was prepared at low temperature by a simple method. The title material was characterized by TEM, XRD, FTIR and BET, respectively. The photocatalytic activity of the as-prepared TiO₂ was evaluated by the degradation of methyl orange solution under sunlight and the photocatalytic oxidation of acetone in air. The results showed that the titanium dioxide hydrosol was composed of anatase phase with average grain size of about 7 nm, and the crystallinity became more perfect with the increase of temperature. The BET surface areas were more than 220 m²·g^-1 for these samples. It is found that the photocatalytic activity was much better for the higher heat processing temperature. Especially, the photocatalytic activity of the sample with a heat treatment of 110 ℃ was better than that of P25. In addition, TiO₂ hydrosol also possessed good photocatalytic activity under the sunlight illumination.     

Si5P6O25∶Tb3+的结构与荧光性质

Tb³⁺ ions were incorporated in P-Si matrix material through a sol-gel process. Luminescence properties of Tb³⁺ as a function of dopant， firing temperature， composition and structure of matrices were investigated. The gels synthesized by the reaction of P₂O₅ or H₃PO₄ with tetraethoxy silane and TbCl₃ as dopant were fired in air from the temperature 25～1000℃ to form P-Si crystalline phase. The crystal structure was determined by powder X-ray diffraction. Si₅O(PO₄)₆ were the only crystalline phase and belong to hexagonal crystal system. The emission of ⁵D₄-⁷F₅(～545nm) transition of Tb³⁺ in the P-Si system is composed of two peaks. The amount of doping Tb³⁺ varied from 0.664% to 1.644%， and no obvious concentration quenching was observed in this doping concentra-tion range. The intensity of Tb³⁺ emission increased with firing temperature increasing and becomes stable at 800～1000℃.     

合成大比表面γ-Mo2N的新方法

The production of high specific surface area γ-Mo₂N (up to 165 m²·g^-1, passivated) by temperature programmed reaction of MoO₃ with mixtures of N₂ and H₂ was reported. The synthetic condition of high surface area γ-Mo₂N (usually, S_BET>100 m²·g^-1) were quite difficult and the amount of starting material MoO₃ in each batch was much less than 0.5 gram. However, some synthetic conditions had been greatly improved in our experiments. The crystalline phase and specific surface area had been characterized by XRD and BET. The XRD gave some information for reaction mechanism.     

纳米晶SnO2粉体的合成

Crystalline tin oxide nanoparticles were synthesized by the direct precipitation from the starting material granulated tin. TG-DTA of the precursor showed a heavy weight loss at about 130℃ accompanied by an endothermic peak， two exothermic peaks above 200℃ accompanied by small weight loss indicated the decomposition and the oxidation of residual NO₃^- ion and PEG. XRD showed that obtained particles agreed well with the determination result of bulk SnO₂. The broadened XRD patterns became sharper as the calcining temperature turned to higher， it was indicated that the growth of the particle was exhibited. The surface area of the particles calcined at 300℃ was 161.1m²·g^-1 and declined as the calcining temperature turned to higher. TEM showed an heavier agglomeration at higher temperature.     

无氨湿法制备纳米晶In2O3及表征

Preparation of In₂O₃nano-scale powders by ultrasonic and homogeneous precipitation, using metal In and urea as raw materials, was reported for the first time, while the effects of reaction temperature, the ratio of the materials and the pH etc. on the preparation was dicussed. This method can be operated and industrialized easily with very low cost． The structural properties of precursor and In₂O₃were characterized by TG-DTA, XRD, ESCA and TEM. The results show that In₂O₃produced are very pure, monophase and spherical nano-scale powders with average size of 25 nm.     

Nafion? / TiO2复合膜的质子传导性能研究

Nafion^® / TiO₂ composite membranes were prepared by in-situ chemical reaction method using Ti(OC₄H₉)₄ and Nafion^® 117 as raw materials. The membranes were characterized by UV, FTIR-ATR and XRD, respectively. Methanol permeability and water uptake were investigated as a function of TiO₂ contents. The conductivity of the membranes was measured under water vapor pressure (2.644 7 kPa) or in dry atmospheres. The XRD results showed that the titanium dioxide in Nafion^® membranes were crystallized in anatase phase with an average crystaline diameter of 3.0 nm. The water uptake of the composite membranes was larger than that of the pure Nafion^® membrane when the TiO₂ loading was within 14wt%. The methanol permeability of the membrane decreased as the TiO₂ loading increased. The addition of 3wt% TiO₂ to Nafion^® membranes improved the conductivity in dry measurement conditions. The proton conductivity of the composite membrane increased greatly after the hydrothermal treatment at 160 ℃ for 2 hours.     

(Ag0.9Li0.1)(Nb1-yTay)O3纳米瓷粉的制备与表征

A series of (Ag_0.9Li_0.1)(Nb_1-yTa_y)O₃ ceramic powders were prepared by an aque-chemical method. The optimized calcination temperature, time and crystal lattice were studied by TG-DTA, IR, XRD and TEM. The results show that the optimized conditions were calcination of the precursor at 800 ℃ for 2 h. The ceramic powder thus prepared was rhombohedral with the average grain size of 48 nm.     

球形La2O3∶Eu纳米晶的制备及其发光特性

The spheric La₂O₃∶Eu nanocrystals were prepared using NH₃·H₂O-NH₄HCO₃ mixture as precipitant. The material was characterized by FTIR, XRD and TEM techniques. The luminescence properties of Eu³⁺ in spheric La₂O₃ were measured by three dimension spectra, emission and excitation spectra. The results indicate that the La₂O₃∶Eu nanocrystals are in hexagonal phase by annealing at 800 ℃, the crystal size is about 30 nm. The maximum emission and excitation wavelength were determined by three dimensional spectroscopy to be at 591 nm and 394 nm, respectively. In emission spectrum the band at 591 nm and 612 nm are corresponding to ⁵D₀-⁷F₁ and ⁵D₀-⁷F₂ transition of Eu³⁺ ions. With increasing in annealing temperature the differences of intensity of the two transitions are increased. This phenomenon shows that the luminescence intensity of La₂O₃∶Eu nanocrystals can be tuned by changing annealing temperature.     

锂离子电池正极材料LiNi1-xCoxO2的合成及电化学性能研究

LiNi_1-xCo_xO₂ cathode materials for lithium ion batteries were synthesized by the co-precipitation and solid-state reaction methods with LiOH·H₂O, Ni(NO₃)₂·6H₂O and Co(NO₃)₂·6H₂O as raw materials. The materials were characterized by XRD, SEM and electrochemical tests. The results showed that synthesized cathode materials were with layered structure similar to α-NaFeO₂ and uniform morphology and nearly normal grain size distribution and better electrochemical performance when x was 0.18. The first charge and discharge capacity of the cathode material was 224.3 mAh·g^-1 and 194.2 mAh·g^-1, respectively. 88.5% of the first discharge capacity remained at the 20th cycle.     

Sc2MgGa2 and Y2MgGa2

Scandium magnesium gallide, Sc₂MgGa₂, and yttrium magnesium gallide, Y₂MgGa₂, were synthesized from the corresponding elements by heating under an argon atmosphere in an induction furnace. These intermetallic compounds crystallize in the tetragonal Mo₂FeB₂‐type structure. All three crystallographically unique atoms occupy special positions and the site symmetries of (Sc/Y, Ga) and Mg are m2m and 4/m, respectively. The coordinations around Sc/Y, Mg and Ga are pentagonal (Sc/Y), tetragonal (Mg) and triangular (Ga) prisms, with four (Mg) or three (Ga) additional capping atoms leading to the coordination numbers [10], [8+4] and [6+3], respectively. The crystal structure of Sc₂MgGa₂ was determined from single‐crystal diffraction intensities and the isostructural Y₂MgGa₂ was identified from powder diffraction data.     

Zur Kenntnis der Dialkalimetalldichalkogenide β-Na2S2, K2S2, α-Rb2S2, β-Rb2S2, K2Se2, Rb2Se2, α-K2Te2, β-K2Te2 und Rb2Te2

On Dialkali Metal Dichalcogenides β-Na₂S₂, K₂S₂, α-Rb₂S₂, β-Rb₂S₂, K₂Se₂, Rb₂Se₂, α-K₂Te₂, β-K₂Te₂ and Rb₂Te₂ The first presentation of pure samples of α- and β-Rb₂S₂, α- and β-K₂Te₂, and Rb₂Te₂ is described. Using single crystals of K₂S₂ and K₂Se₂, received by ammonothermal synthesis, the structure of the Na₂O₂ type and by using single crystals of β-Na₂S₂ and β-K₂Te₂ the Li₂O₂ type structure will be refined. By combined investigations with temperature-dependent Guinier-, neutron diffraction-, thermal analysis, and Raman-spectroscopy the nature of the monotropic phase transition from the Na₂O₂ type to the Li₂O₂ type will be explained by means of the examples α-/β-Na₂S₂ and α-/β-K₂Te₂. A further case of dimorphic condition as well as the monotropic phase transition of α- and β-Rb₂S₂ is presented. The existing areas of the structure fields of the dialkali metal dichalcogenides are limited by the model of the polar covalence.     

Crystal Structures of [Bu2Sn(O2PPh2)2], [Ph2Sn(O2PPh2)2], and [PhClSn(O2PPh2)OMe]2. Raman Spectra of [Ph2Sn(O2PPh2)2] and [PhClSn(O2PPh2)OMe]2

[(n‐Bu)₂Sn(O₂PPh₂)₂] ( 1 ), and [Ph₂Sn(O₂PPh₂)₂] ( 2 ) have been synthesized by the reactions of R₂SnCl₂ (R=n‐Bu, Ph) with HO₂PPh₂ in Methanol. From the reaction of Ph₂SnCl₂ with diphenylphosphinic acid a third product [PhClSn(O₂PPh₂)OMe]₂ ( 3 ) could be isolated. X‐ray diffraction studies show 1 to crystallize in the monoclinic space group P2₁/c with a = 1303.7(1) pm, b = 2286.9(2) pm, c = 1063.1(1) pm, β = 94.383(6)°, and Z = 4. 2 crystallizes triclinic in the space group , the cell parameters being a = 1293.2(2) pm, b = 1478.5(4) pm, c = 1507.2(3) pm, α = 98.86(3)°, β = 109.63(2)°, γ = 114.88(2)°, and Z = 2. Both compounds form arrays of eight‐membered rings (SnOPO)₂ linked at the tin atoms to form chains of infinite length. The dimer 3 consists of a like ring, in which the tin atoms are bridged by methoxo groups. It crystallizes triclinic in space group with a = 946.4(1) pm, b = 963.7(1) pm, c = 1174.2(1) pm, α = 82.495(6)°, β = 66.451(6)°, γ = 74.922(6)°, and Z = 1 for the dimer. The Raman spectra of 2 and 3 are given and discussed.     

Thermal decomposition of Me3SnO2PCl2, Me2Sn(O2PCl2)2 and Ph3SnO2PCl2

TG and DTA studies on Me₃SnO₂PCl₂, Me₂Sn(O₂PCl₂)₂ and Ph₃SnO₂PCl₂ were carried out under dynamic argon atmosphere. The results show that the decomposition proceeds in different stages leading to the formation of Sn₃(PO₄)₂ as a stable product. This compound was characterized by IR spectroscopy. Decomposition schemes involving reductive elimination reactions were proposed.     

The alkali hypophosphites KH2PO2, RbH2PO2 and CsH2PO2

The structures of the hypophosphites KH₂PO₂ (potassium hypophosphite), RbH₂PO₂ (rubidium hypophosphite) and CsH₂PO₂ (caesium hypophosphite) have been determined by single‐crystal X‐ray diffraction. The structures consist of layers of alkali cations and hypophosphite anions, with the latter bridging four cations within the same layer. The Rb and Cs hypophosphites are isomorphous.     

Electrochemical study of (NEt4)2Cl2FeS2MoS2 and (NEt4)2Cl2FeS2MoS2FeCl2

Summary The ability of [MoS₄]^2–, anions to be used as ligands for transition metal ions has been widely demonstrated, especially with Fe²⁺. The present study has been restricted to linear complexes such as (NEt₄)₂ [Cl₂FeS₂MoS₂] and (NEt₄)₂[Cl₂FeS₂MoS₂FeCl₂]. Their electrochemical properties are described: upon electrochemical reduction, these compounds yield MoS₂, as a black precipitate, and an iron complex in solution, assumed to be [SFeCl₂]^2–. The electrochemical reduction goes through two electron transfers, coupled with the breakdown of the molecular skeleton: a DISPl and an ECE mechanism. Depending on the solvent, the following equilibrium may be observed: [Cl₄Fe₂MoS₄]^2–[Cl₂FeMoS₄]^2–+FeCl₂. The equilibrium constant, K_D, was evaluated by differential pulse polarography. K_D is tightly related to the donor number of the solvent.     

Formal [(2+2)+2] and [(2+2)+(2+2)] nonconjugated dienediyne cascade cycloadditions

[reaction: see text] Fluoranthene 2 and heptacycle 3 are easily accessible from the reaction of diyne 1 and norbornadiene (NBD) in the presence of the rhodium catalyst. The unusual [(2+2)+(2+2)] adduct 3 was confirmed by the X-ray crystal structure analysis.